Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Radiative conductivity in the Earth’s lower mantle

Nature volume 456, pages 231–234 (2008)Cite this article

Abstract

Iron in crustal and mantle minerals adopts several possible oxidation states: this has implications for biogeochemical processes1, oxygenation of the atmosphere2 and the oxidation state of the mantle3,4. In the deep Earth, iron in silicate perovskite, (Mg0.9Fe0.1)SiO3, and ferropericlase, (Mg0.85Fe0.15)O, influences the thermal conductivity of the lower mantle and therefore heat flux from the core. Little is known, however, about the effect of iron oxidation states on transport properties. Here we show that the radiative component of thermal conductivity in the dominant silicate perovskite material of Earth’s lower mantle is controlled by the amount of ferric iron, Fe3+. We obtained the optical absorption spectra of silicate perovskite and ferropericlase at pressures up to 133 GPa, corresponding to pressures at the core–mantle boundary. Absorption spectra of ferropericlase up to 800 K and 60 GPa exhibit minimal temperature dependence. The results on silicate perovskite show that optical absorption in the visible and near-infrared spectral range is dominated by O–Fe3+ charge transfer and Fe3+–Fe2+ intervalence transitions, whereas a contribution from the Fe2+ crystal-field transitions is substantially smaller. The estimated pressure-dependent radiative conductivity, krad, from these data is 2–5 times lower than previously inferred from model extrapolations, with implications for the evolution of the mantle, such as generation and stability of thermo-chemical plumes in the lower mantle.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Optical absorption spectra of silicate perovskite (10 mol% Fe) up to 133 GPa at room temperature in various pressure media.
Figure 2: Radiative part of the Earth’s lower-mantle thermal conductivity as a function of depth.

Similar content being viewed by others

References

  1. Johnson, C. M. & Beard, B. L. Biogeochemical cycling of iron isotopes. Science 309, 1025–1027 (2005)

    Article  CAS  Google Scholar 

  2. Rouxel, O. J., Bekker, A. & Edwards, K. J. Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state. Science 307, 1088–1091 (2005)

    Article  ADS  CAS  Google Scholar 

  3. McCammon, C. Perovskite as a possible sink for ferric iron in the lower mantle. Nature 387, 694–696 (1997)

    Article  ADS  CAS  Google Scholar 

  4. Frost, D. J. et al. Experimental evidence for the existence of iron-rich metal in the Earth’s lower mantle. Nature 428, 409–412 (2004)

    Article  ADS  CAS  Google Scholar 

  5. Zhong, S. Constraints on thermochemical convection of the mantle from plume heat flux, plume excess temperature, and upper mantle temperature. J. Geophys. Res. 111 B04409 doi: 10.1029/2005JB003972 (2006)

    Article  ADS  Google Scholar 

  6. Yanagawa, T. K. B., Nakada, M. & Yuen, D. A. Influence of lattice thermal conductivity on thermal convection with strongly temperature-dependent viscosity. Earth Planets Space 57, 15–28 (2005)

    Article  ADS  Google Scholar 

  7. Hofmeister, A. M. Mantle values of thermal conductivity and the geotherm from phonon lifetimes. Science 283, 1699–1706 (1999)

    Article  ADS  CAS  Google Scholar 

  8. Hofmeister, A. M. & Yuen, D. A. Critical phenomena in thermal conductivity: Implications for lower mantle dynamics. J. Geodyn. 44, 186–199 (2007)

    Article  Google Scholar 

  9. Dubuffet, F., Yuen, D. A. & Rainey, E. S. G. Controlling thermal chaos in the mantle by positive feedback from radiative thermal conductivity. Nonlin. Process. Geophys. 9, 1–13 (2002)

    Article  Google Scholar 

  10. van den Berg, A. P., Rainey, E. S. G. & Yuen, D. A. The combined influences of variable thermal conductivity, temperature- and pressure-dependent viscosity and core–mantle coupling on thermal evolution. Phys. Earth Planet. Inter. 149, 259–278 (2005)

    Article  ADS  Google Scholar 

  11. Clark, S. P. Radiative transfer in the Earth’s mantle. Trans. Am. Geophys. Union 38, 931–938 (1957)

    Article  ADS  Google Scholar 

  12. Shankland, T. J., Nitsan, U. & Duba, A. G. Optical absorption and radiative heat transport in olivine at high temperature. J. Geophys. Res. 84, 1603–1610 (1979)

    Article  ADS  CAS  Google Scholar 

  13. Burns, R. G. Mineralogical Applications of Crystal Field Theory 2nd edn (Cambridge Univ. Press, 1993)

    Book  Google Scholar 

  14. Sherman, D. M. The high-pressure electronic structure of magnesiowüstite (Mg,Fe)O: Applications to the physics and chemistry of the lower mantle. J. Geophys. Res. 96, 14299–14312 (1991)

    Article  ADS  CAS  Google Scholar 

  15. Badro, J. et al. Transitions in perovskite: Possible nonconvecting layers in the lower mantle. Science 305, 383–386 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Ross, R. G., Andersson, P., Sundqvist, B. & Bäckström, G. Thermal conductivity of solids and liquids under pressure. Rep. Prog. Phys. 47, 1347–1402 (1984)

    Article  ADS  CAS  Google Scholar 

  17. Mao, H. K. & Bell, P. M. Electrical conductivity and the red shift of absorption in olivine and spinel at high pressure. Science 176, 403–406 (1972)

    Article  ADS  CAS  Google Scholar 

  18. Keppler, H. & Smyth, J. R. Optical and near infrared spectra of ringwoodite to 21.5 GPa: Implications for radiative heat transport in the mantle. Am. Mineral. 90, 1209–1212 (2005)

    Article  ADS  CAS  Google Scholar 

  19. Pertermann, M. & Hofmeister, A. M. Thermal diffusivity of olivine-group minerals at high temperature. Am. Mineral. 91, 1747–1760 (2006)

    Article  ADS  CAS  Google Scholar 

  20. Goncharov, A. F., Struzhkin, V. V. & Jacobsen, S. D. Reduced radiative conductivity of low-spin (Mg,Fe)O in the lower mantle. Science 312, 1205–1208 (2006)

    Article  ADS  CAS  Google Scholar 

  21. Keppler, H., Kantor, I. & Dubrovinsky, L. S. Optical absorption spectra of ferropericlase to 84 GPa. Am. Mineral. 92, 433–436 (2007)

    Article  ADS  CAS  Google Scholar 

  22. Keppler, H., McCammon, C. A. & Rubie, D. C. Crystal-field and charge-transfer spectra of (Mg,Fe)SiO3 perovskite. Am. Mineral. 79, 1215–1218 (1994)

    CAS  Google Scholar 

  23. Shen, G., Fei, Y., Hålenius, U. & Wang, Y. Optical absorption spectra of (Mg,Fe)SiO3 silicate perovskites. Phys. Chem. Miner. 20, 478–482 (1994)

    Article  ADS  CAS  Google Scholar 

  24. Mattson, S. M. & Rossman, G. R. Identifying characteristics of charge transfer transitions in minerals. Phys. Chem. Miner. 14, 94–99 (1987)

    Article  ADS  CAS  Google Scholar 

  25. Bocquet, A. E. et al. Electronic structure of early 3d-transition-metal oxides by analysis of the 2p core-level photoemission spectra. Phys. Rev. B 53, 1161–1170 (1996)

    Article  ADS  CAS  Google Scholar 

  26. Badro, J. et al. Iron partitioning in Earth’s mantle: Toward a deep lower mantle discontinuity. Science 300, 789–791 (2003)

    Article  ADS  CAS  Google Scholar 

  27. Li, J. et al. Pressure effect on the electronic structure of iron in (Mg,Fe)(Si,Al)O3 perovskite: A combined synchrotron Mössbauer and X-ray emission spectroscopy study up to 100 GPa. Phys. Chem. Miner. 33, 575–585 (2006)

    Article  ADS  CAS  Google Scholar 

  28. Turcotte, D. L. & Schubert, G. Geodynamics (Cambridge Univ. Press, 2002)

    Book  Google Scholar 

  29. Montague, N. L., Kellogg, L. H. & Manga, M. High-Rayleigh number thermo-chemical models of a dense boundary layer in D. Geophys. Res. Lett. 25, 2345–2348 (1998)

    Article  ADS  CAS  Google Scholar 

  30. Naliboff, J. B. & Kellogg, L. H. Can large increases in viscosity and thermal conductivity preserve large-scale heterogeneity in the mantle? Phys. Earth Planet. Inter. 161, 86–102 (2007)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We acknowledge support from NSF/EAR, DOE/BES, DOE/NNSA (CDAC) and the W. M. Keck Foundation. S.D.J. thanks D. J. Frost, S. J. Mackwell and D. P. Dobson for help with sample synthesis, C. A. McCammon for Mössbauer spectroscopy, J. R. Smyth for single-crystal X-ray diffraction, H. Watson for electron microprobe analysis of the silicate perovskite material and the NSF and Bayerishes Geoinstitut Visitor’s Program for support. B.D.H. was supported by the NSF Research Experience for Undergraduates (REU) Program at the Carnegie Institution of Washington. P.B. was partially supported by the Balzan Foundation.

Author Contributions A.F.G., V.V.S. and S.D.J. designed the research programme; S.D.J. synthesized and polished the single crystals; A.F.G. and B.D.H. performed high-pressure experiments at room temperature; A.F.G., V.V.S. and P.B. performed high-temperature experiments; A.F.G., V.V.S., B.D.H. and P.B. analysed the data; P.B. developed a thermal conductivity model; V.V.S, A.F.G. and S.D.J interpreted the results; A.F.G, S.D.J., P.B. and V.V.S. wrote the paper. All authors discussed the results and commented on the manuscripts.

Author information

Authors and Affiliations

  1. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington DC 20015, USA ,

    Alexander F. Goncharov, Benjamin D. Haugen, Viktor V. Struzhkin & Pierre Beck

  2. Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309, USA,

    Benjamin D. Haugen

  3. Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois 60208, USA,

    Steven D. Jacobsen

Authors
  1. Alexander F. Goncharov
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Benjamin D. Haugen
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Viktor V. Struzhkin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Pierre Beck
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Steven D. Jacobsen
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Alexander F. Goncharov.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Supplementary Figures S1-S3 with Legends and Supplementary References. (PDF 330 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Goncharov, A., Haugen, B., Struzhkin, V. et al. Radiative conductivity in the Earth’s lower mantle. Nature 456, 231–234 (2008). https://doi.org/10.1038/nature07412

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature07412

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing